Smith started the race in 23rd and was still outside the top 10 with under than 70 laps to go. But he stayed out on old tires during a caution nine laps from the end to take the lead and held off series points leader Carl Edwards in the two-lap overtime to win for the first time in 105 career starts.

"I'm not supposed to win this race. I've never even had a top-five. I guess in this series, it just shows anyone can win," said Smith, whose previous best this season was a seventh at Daytona.

While the 27-year-old Smith, was celebrating, tempers erupted behind him after Kevin Harvick, Kyle Busch and Clint Bowyer tangled in an accident that set up the finish.

After the race, Harvick tracked down Busch's car, stopped in front of Busch on pit road, then got out of his car and attempted to punch or grab Busch through his window. Busch then slammed into Harvick's driverless car, sending it crashing in the inside wall.

Harvick and Busch then stared down each other from their cars as they entered the garage before a standoff that looked as if it might erupt further. It finally ended when Busch bumped Harvick several times to make space to drive off. Both drivers were summoned to the NASCAR hauler.

Edwards appeared to be cruising to his first Darlington victory with 10 laps remaining in what had been about 490 miles of relatively calm racing. Instead, things changed when Jeff Burton brought out the 10th and final caution, setting up a restart with five laps left and many of NASCAR's best not far from the lead.

Busch, Harvick and Bowyer wound up three-wide in a space where that doesn't work and Bowyer was sent sprawling into the interior wall. As cars spun out behind, Busch gathered his car, then veered down the track and sent Harvick spinning.

Smith bobbled slightly on the final lap, but regained control and took off for the victory. He was in tears in victory lane, winning for the first time in 105 Sprint Cup starts.

"We've had some ups and we've had some downs, this is an up," Smith said.

Smith's landmark win, though, will likely be overlooked with the dustup between Harvick and Busch, who have a history. Harvick admittedly wrecked Busch on purpose late in last season's finale at Homestead as retaliation for earlier contact.

"Just uncalled for. Just unacceptable racing," Busch said. "You know, it's in the last couple of laps but I gave him room off of two, I didn't get the room. Just real unfortunate. I hate we tore up a few good cars there."

Busch said the talk in NASCAR's hauler was not a big deal. "Good to hash it out now. Might as well," he said.

Harvick says he was racing hard "and doing what we had to do there at the end and things happen."

Was it over?

"You saw the end," Harvick said, smiling, as he walked off.

Edwards says all drivers have a passion for racing that can leave them frustrated at times. "This is racing," he said. "You're going to have stuff like that. I think all of us know that can happen and we should be prepared."

Smith said he was too overjoyed to pay attention to the problems behind him. "I have no clue what happened in the race other than us winning," he said. "And you know what? If (feuds) are what's talked about next week, so be it."

The spotlight figured to be on Newman and Juan Pablo Montoya, who tangled at Richmond International Raceway a week earlier -- a feud that continued into this week at Darlington.

But those two mostly stayed away from each other. Montoya did get into five-time defending champion Jimmie Johnson early on. Montoya apologized for tagging Johnson. "I bet he's sorry," Johnson responded.

Before the end, the most frightening incident came when the nose of David Ragan's car peeled off the sheet metal on the left side of Brian Vicker's machine, leaving a long trail of debris.